Photographic information setting device for a camera

ABSTRACT

A photographic information setting device for a camera according to the present invention includes a film speed reader which reads out a film speed value provided on a film container, a micro computer and three memories. A first memory is for storing a film speed value of a film in use, a second memory is for storing a film speed value of a film used immediately before the film in use, and a third memory is for storing a film speed value to be used in deciding an exposure value for a camera. The micro computer compares the film speed values in the first and second memories and, when the two values are the same, it controls in such a manner that the film speed value in the third memory may not be altered. On the other hand, when the two values are different, the micro computer controls in such a manner that the film speed value in the first memory may be stored in the second and third memories.

BACKGROUND OF THE INVENTION

The present invention relates to a photographic information settingdevice for a camera which reads out a DX code on a film container andsets photographic information for the camera in accordance with the readDX code.

Conventionally, there is a device which has been proposed as aphotographic information setting device. The device comprises first andsecond ISO registers. The first register is for storing ISO value whichis obtained by decoding a DX code read out by a DX code readout means.On the other hand, the second ISO register stores ISO values forcontrolling the photographic operation of a camera or ones to bedisplayed. When a camera provided with the photographic informationsetting device is laoded with a new film, the device reads out a DX codeon a container of the film and decodes it to obtain a corresponding ISOvalue, so that data in each of the first and second ISO registers arerenewed according to the obtained ISO value.

The renewal of data in the first and second ISO registers is effectedautomatically under any condition when the DC code is read out by the DXcode readout means. Consequently, in the case that the newly loaded filmis of the same ISO value as the previously used film, the followingproblem occurs. Assume that such film change is done while aphotographer is taking pictures under the conditions where the filmspeed of the previous film has been corrected by the photographer, inother words, data in the second ISO register has been corrected, thusbeing different from a ISO value which corresponds to the DX code forthe previous film and is stored in the first ISO register. In this case,according to the conventional device, data in the second ISO registervalue never fails to be changed to the ISO value corresponding to the DXcode newly read out, i.e., the same value as the ISO value stored in thefirst ISO register prior to the film change. The photographer must dothe same operation again in order to correct the data in the second ISOregister as before, thus causing much troublesomeness.

SUMMARY OF THE INVENTION

Accordingly, the object of the present invention is to provide anphotographic information setting device for a camera which, in case thatthe DX code for a newly loaded film is the same as the DX code for thepreceding film, is adapted to maintain data in the second ISO registerand does not adopt the ISO value corresponding to the DC code for thenew film as a value which is used for controlling the operation of acamera or displayed.

In order to accomplish the object, a photographic information settingdevice for a camera of the present invention is characterized in that itcomprises: an automatic film speed reading means for automaticallyreading out a film speed value, of a film in use, provided on acontainer of the film; a first memory means for storing a film speedvalue, of an actual film; read out by the automatic film speed readingmeans; a second memory means for storing a film speed value, of a filmused immediately before a film in use, read out by the automatic filmspeed reading means; a third memory means for storing a film speed valueto be used in deciding an exposure value for a camera; a film speedaltering means for altering a film speed value stored in the thirdmemory means to another film speed value and supplying the third memorymeans with the latter value to be stored therein; a comparing means forcomparing a film speed value stored in the first memory means with onestored in the second memory means; and a controlling means forcontrolling in such a manner that, when the comparison effected by thecomparing means results in that the film speeds in the first and secondmemory means are the same, alteration of a film speed value stored inthe third memory means may not be carried out, while, when the filmspeeds in the first and second memory means are different from eachother as a result of the comparison, the film speed value in the firstmemory means may be stored in both of the second and third memory means.

The photographic information setting device for a camera of the presentinvention functions as follows:

When the automatic film speed reading means reads out a film speed valueprovided on a container of a film in use, the film speed value read outis provided to the first memory means to get stored therein asinformation relative to the film in use. Then, the comparing meanscompares the film speed value in the first memory means with data, inthe second memory means, which represents the film speed value of theprevious film. If the comparison result indicates that the two filmspeed values are the same, the controlling means causes the third memorymeans to keep holding data which has been stored therein. On the otherhand, if the two film speed values are different from each other, thecontrolling means causes the third memory means to alter the previousdata to data corresponding to the film speed value stored in the firstmemory means. Owing to this structure, once a photographer completes thecorrection of the film speed of a film in use, the photographer is notrequired to carry out such a correction again when he replaces the filmwith a new film of the same type or when he replaces a dead battery.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a block daigram illustrative of an embodiment of the presentinvention;

FIG. 2 shows, with respect to the option mode and normal mode, thesequences in which the exposure mode is altered;

FIGS. 3 through 6, 8 through 10, and 12 explain, by way of a flowchart,the preparing operation for photographing according to the embodiment;

FIG. 7 shows the relationship between the exposure modes and theexposure mode selection switch at its "on" and "off" positions;

FIG. 11 shows examples of photographing information shown on thedisplay; and

FIG. 13 shows another example of photographing information shown in thedisplay.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The diagram of FIG. 1 shows a microcomputer 1 which performs asequential control, exposure computation, etc. of a camera, a lightmeasuring portion 2 which measures the luminance of an object, a lensinformation memory circuit 3, a DX code readout portion 4, a displayportion 7 which consists of a microcomputer 5 for display and a liquidcrystal display (LCD) 6, and an exposure controller 8.

The light measuring portion 2 receives electric signals from a lightreceiving element such as a silicon photoelectric cell (SPC), whichpeforms photoelectric conversion of light inputted through a lens (notshown in the drawings). Then, the light measuring portion 2 converts theinput signals into the digital form and outputs corresponding luminance(BV) in terms of apex value to the microcomputer 1. The lens informationmemory circuit 3 is a circuit for storing lens information of a settledlens and provides a fully opened aperture value (AV₀) in terms of apexvalue in the form of digital signals to the microcomputer 1. The DX codereadout portion 4 reads out the electric code (hereinafter referred toas "DX code") which is carried by a film cassette loaded and representsfilm information such as film speed and the like, and supplies the DXcode in the form of a digital signal to the microcomputer 1. Themicrocomputer 5 for display in the display portion 7 receives data forthe display outputted by the microcomputer 1, decodes them, and providesthe results to the liquid crystal display (LCD) 6 for the relevantdisplay. The exposure control unit 8 controls the exposure in responseto a relevant depression of the release button and on the basis ofexposure information determined by the microcomputer 1.

A switch denoted by S1 is one for preparing the camera forphotographing, which is turned on by a first depressing stroke of therelease button (not shown in the drawings). When this switch S1 isturned on, an impulse is inputted through a one-shot circuit 9 to themicrocomputer 1 at the interrupt terminal IINT, so that themicrocomputer 1 executes an interruptive routine INTRPT (describedlater) for preparing the camera for photoghaphing, such a preparingoperation including input of photographing information (describedlater), exposure computation, and display of photographing information.A switch denoted by S2 is a release switch which is turned on by asecond depressing stroke (a stroke deeper than the first depressingstroke) of the release button not shown. When this release switch S2 isturned on, the exposure control is carried out.

A switch denoted by S ISO is one for altering the film speed. When thisswitch S ISO and either an up-switch denoted by S TU or a down-switch STD, both the two latter switches being disposed at the upper part of thecamera body, are turned on, the film speed vaue is altered by adding orsubtracting a value corresponding to 1/3 EV. A switch denoted by S +/-is one for correcting the exposure. In one case, when this exposurecorrecting switch S +/- is turned on, it maintains the exposurecorrecting mode and in the other case, the switch permits the exposureamount correction to be carried out only when it has been turned on. Ineither case, when this switch is used in conjunction with either theup-switch S TU or down-switch S TD disposed at the upper part of thecamea body, it permits the exposure to be corrected in increments ordecrements corresponding to 1/2 EV. A switch denoted by S AEL is an AElock switch, which is used to memorize the exposure value (Thisoperation will hereinafter be referred to as "AE lock" ). A first turnof this switch S AEL sets an AE lock and a second turn of the switchends the AE lock.

A switch denoted by the S LAMP is a photographic informationilluminating switch, which is used to illuminate the display in aviewfinder. The illumination goes on by a single operation such as adepressing stroke, for example, of the switch, and goes off as thesource power is cut off. Each of switches denoted by S MD0, S MD1 and SMD2 is a mode judgment switch, whose "on" or "off" is decided accordingto which one mode is selected by button manipulation from among thefollowing five exposure modes: programmed automatic exposure controlmode (hereinafter referred to as P mode), shutter priority automaticexposure control mode (hereinafter referred to as S mode), aperturepriority automatic exposure control mode (hereinafter referred to as Amode), first manual exposure control mode (hereinafter referred to as Mmode), and second manual exposure control mode (hereinafter referred toas M/2 mode which is capable of altering set values for photographicinformation (AV, TV) by value corresponding to 1/4 EV, which is a halfof the value by which the set values for photographic information are tobe altered, in the P, S, A or M mode. The microcomputer 1 judges theexposure mode selected by the photographer on the basis of therelationship between the respective exposure modes and the combinationsof "ons" and "off" of the mode judgement switches S MD0, S MD1, and SMD2. A switch denoted by S RC is linked wih the rear lid in such amanner that this switch is turned on when the rear lid is opened andturned off when it is closed. The up-switch S TU and down-switdh S TD,disposed at the upper part of the camera body, are used not only forcorrecting the exposure amount and altering the film speed in the mannerof addition or subtraction as described hereinbefore but also foraltering the shutter speed in M mode or M/2 mode and for altering thepriority values in S mode or A mode. Switches denoted as S AU and S AD,disposed beside the lens mount, are an up-switch and a down-switchrespectively which are used for increasing or decreasing the aperturesize in M mode or M/2 mode and also for increasing or deceasing thepriority values in the S mode or A mode.

Switches denoted by S OP1, S OP2 and S OP3 are optional switches whichare used to alter some specific functions as desired by thephotographer. The switch S OP1 is used to alter the sequence in whichthe exposure modes (P, S, A, M, and M/2) are selected when the modeselection is altered. When the switch S OP1 is on, the sequence is asshown in the a of FIG. 2 (option mode), and, when the switch is off, thesequence is as shown in the b of FIG. 2 (normal mode). The switch S OP2is used to alter the relationship between the AE lock and the powersource retention of the camera. This switch S OP2 when turned onactuates a timer for the power source retention, and, when the timerwinds down or completes the specified time counting, the power sourceretention and AE lock are ended. When the switch S OP2 is off, the timerdoes not function and the power source is retained while AE lock is inoperation. The switch S OP3 is used to alter the duration for which thepower source is retained. When this switch S OP3 is off, the powersource is retained for 10 seconds (after the switch S1 has been turnedoff), and, when the switch S OP3 is on, the duration of power sourceretention is altered to 15 seconds. These optional switches are not usedin general, except when some alterations are desired by thephotographer. However, to render it simple to make such alterations whenrequired, these switches are disposed at positions where they areconveniently handled by simply removing the identification plate, i.e.,the bottom cover of the camera body or the top cover.

A light-emitting diode denoted by LED 1 is to illuminate the inside ofthe viewfinder and one denoted by LED 2 is, when the AE lock is inoperation, to indicate its in-operation in the viewfinder.

A photographic information-setting device of a camera provided with thephotographic information setting and displaying devices of the abovedescribed construction operates as follow:

When a battery V AM is put in place, a signal "H" is inputted to themicrocomputer 1 through the terminal RST so that the microcomputer 1executes a rest routine as shown in FIG. 3.

At Step #1, RAM (read only memory) and the output ports in themicrocomputer 1 are initialized.

At Step #2, a film speed ISO100 (i.e. SV=5) is stored in ISO register.The control and display of the exposure of the camera are based on thefilm speed SV (hereinafter referred to as "ISO value") represented by anapex value stored in this ISO register.

At Step #3, the DX code on the film cassette is read out and decoded.

The routine for reading out and decoding the DX code is described indetail hereinafter with reference to FIG. 4.

At Step #100, the microcomputer 1 reads out the DX code on the filmcontainer by means of the DX code readout portion 4.

At step #101, it is decided whether or not the film container bears itsDX code. When the film container bears its DX code, the program flowproceeds to Step #102, and if it does not, the program flow proceeds toStep #105.

At Step #102, the DX code read out is decoded into an ISO value (SV).

At Step #103, the ISO value (SV) resulting from the decoding at Step#102 is compared with the data in DX ISO register, i.e., ISO value (SV)of a previous DX code which was stored therein immediately before. Ifthe ISO values differs from each other, the program flow proceeds toStep #104. If those values are the same, Step #104 is skipped.

At Step #104, to which the program flow has proceeded because ofdifference of the ISO value (SV) only just obtained from that stored inDXISO register, in other words, because the film speed of the actuallyused film differs from that of the film used immediately before, thedata in the ISO register and that is DXISO register are superseded withthe current ISO value (SV) which has just been obtained by decoding.

When correction of the film speed has been done with a previous film,loading of a new film of the same film speed as that of the previous oneor replacement of the battery V AM does not require a repeated operationfor correcting the film speed, provided that the film speed correctedprior to the film reloading or battery replacement is retained.

At Step #105, to which the program flow has proceeded from the Step #101because the loaded film container does not bear a DX code, DXISOregister is cleared to "0".

When the film container does not bear a DX code, the DXISO register iscleared to "0" for the following reason. Assume that a film of filmspeed ISO 100 which does not bear a DX code on its container is usedwith the film speed corrected from that ISO 100 to ISO 125 after the useof an ISO 200 film bearing a DX code on its container without film speedcorrection. Thus, the ISO register which controls the exposure of thecamera has the corrected film speed of ISO 125 and the DXISO registerhas ISO 200 which is the film speed of the preceding film. If, next, aISO 200 film which bears a DX code on its container is loaded, the filmspeed newly read out is determined to be identical with that stored inthe DXISO register, so that the routine for reading out and decoding DXcode is executed through Steps #100, #101, #102 and #103 and by skippingStep #104. As a result, the ISO register keeps ISO 125 and the DXISOregister ISO 200. The problem is that the ISO register for controllingthe camera is caused to have ISO 125 although the DX code indicates ISO200, In order to preclude such a problem, when the DX code is found tobe missing from a film container at Step #101, a value which is not usedas an ISO value of DX code ("0" in the embodiment) is stored in DXISOregister at Step #105 so that, when a film bearing its DX code on itscontainer is loaded next, the DX code readout-decoding routine will beexecuted certainly through Step #104 so as to renew the data in ISOregister.

The routine for "reset", which has been described above, is followed byone for "stop," which is illustrated in FIG. 3. In the routine for stop,the microcomputer effects controlling according to the completion of thephotographing.

At Step #4, the microcomputer 1 resets all the output ports and by sodoing turns off the light-emitting diode LED2 whose lighting indicatesthe AE lock being in operation, while it turns off the light-emittingdiode LED1 for illumination in the viewfinder, which has been turned onby the switch S LAMP for the illumination. Thus this diode LED1 for theviewfinder illumination, even though turned on manually, is certain tobe turned off by the microcomputer 1 when it executes the routine for"stop."

At Step #5, the flag AFLF which indicates the AE lock in operation isreset or turned off, and the flag AELOFF which indicates that the AElock switch is off is set or turned on.

At Step #6, to turn off the liquid crystal display 6, a signal forturning off the display is inputted to the microcomputer 5 for display.

At Step #7, the microcomputer 1 stops its controlling, permitting theinterruption for setting or preparing the camera for photographing,which interruption is represented by a depressing of the release button(i.e., the switch S1 for setting the camera for photographing is turnedon).

The following describes the routine of the interruption carried out by afirst depressing stroke of the release button by the photographer, whichturns on the switch S1 for setting the camera for photographing.

At Step #8, to measure the luminance of the object, the microcomputer 1causes the light measuring portion 2 to carry out the photometric actionby providing a relevant signal there.

At Step #9, the timer for power source retention is reset and started.

The details of the routine for resetting and starting the timer aredescribed hereinbelow with reference to FIG. 5.

At Step #200, it is checked whether the optional switch S OP3 is on oroff. If the switch is on, the timer is set for 15 seconds at Step #202,and the routine is followed to Step #203. If the switch is off, thetimer is set for 10 seconds at Step #201, and the routine is followed toStep #203.

At Step #203, the timer is started. After resetting and starting thetimer as above, the program proceeds to Step #10 as shown in FIG. 3.

At Step #10, it is checked whether or not there has been a change withrespect to opening and closing of the rear lid. If there has been achange from the opened state to closure (the rear lid switch S RC hasbeen turned to the "off" position from the on position), the programproceeds to Step #11. Otherwise, Step #11 is skipped.

At Step #11, to which the operation has proceeded because of a change ofthe rear lid from the opened state to closure, a new film is regarded ashaving been loaded and the routine for reading out and decoding the DXcode is carried out, starting with reading out the DX code on the filmcontainer, as shown in FIG. 4, and then the program proceeds to Step#12.

At Step #12, the fully opened aperture value AV₀ of the lens mounted tothe camera is outputted from the lens information memory circuit 3 ofthe lens and stored in a memory (not shown in the drawings).

At Step #13, the exposure mode selected by the photographer is checked.

With reference to FIGS. 6 and 7, the details of the routine for checkingthe exposure mode are described next.

At Step #300, it is checked whether the mode switch S MD1 is off or not.If it is off, the exposure mode selected is discriminated to be one of Mmode, M/2 mode and A mode, as shown in FIG. 7, and the program proceedsto #301. If not, the exposure mode selected is discriminated to beeither the S mode or P mode, and the program proceeds to Step #308.

At Step #301, i is checked whether the mode switch S MD0 is off or not.If it is off, the camera is set to M mode at Step #302, and the programproceeds to Step #303. If the mode switch S MD0 is not off, the exposuremode selected is discriminated to be A mode, and the program proceeds toStep #305.

At Step #303, it is checked whether the mode switch S MD2 is on or not.If it is on, the exposure mode is assumed to be M/2 mode, as shown inFIG. 7, and the exposure mode set at Step #302 is superseded by M/2 modeat Step #304. If the mode switch is off, M mode set at Step #302 isconfirmed, and the program proceeds to Step #307.

At Step #305, to which the operation has proceeded from Step #301because the mode switch S MD0 was found to be on, it is checked whetherthe option switch S OP1 for altering the changing sequence of theexposure modes is on or not. If it is on, the exposure modes arediscriminated to be of the option mode (see the a of FIG. 2), and since,as shown in FIG. 7, the order of arrangement of the exposure modes inthe normal mode (see the b of FIG. 2) is opposite to that in the optionmode with respect to A and P modes, the exposure which was assumed to beof A mode at Step #301 is now regarded as P mode, and so the camera isset to P mode at Step #310, and then, the program proceeds to Step #307.If the option switch S OP1 is off, the camera is set to A mode at Step#306, and the program proceeds to Step #307.

At Step #308, it is checked whether the mode judgement switch S MD0 isoff or not. If it is off, the exposure mode selected is judged to be Pmode, as shown in FIG. 7, and the program proceeds to Step #309. If not,the exposure mode selected is discriminated to be S mode, and so the Smode is set for the exposure mode at Step #311, and the program proceedsto Step #307.

At Step #309, it is checked whether the option switch S OP1 is on ornot. If it is on, the exposure modes are judged to be of the optionmode, and the exposure mode which was regarded as P mode at Step #308 isnow regarded as A mode, and then, the program proceeds to Step #306. Onthe other hand, if the same switch is discriminated to be off, P mode isconfirmed, and the program proceeds to Step #310.

When the exposure mode has been identified as the M/2, M, A, P or S modeat Step #303, #306, #310 or #311 as described above, the programproceeds to Step #307.

The five exposure modes are divided into the following two types inaccordance with changing degrees by which set values representing thephotographic information (AV, TV) are to be varied: a first type mode,which permits a set value to be increased or decreased by a valuecorresponding to 1/2 EV, and a second type mode, which permits a setvalue to be changed at the rate of 1/4 EV in addition to the rate of thefirst type mode. Each of P, S, A and M modes belongs to the first typemode, whereas M/2 mode the second type mode.

At Step #307, when the exposure mode selected is of the first type mode,data AV in the controlled aperture value register AVSET and data TV inthe controlled shutter speed value register TVSET, both for controllingthe exposure of the camera, are shifted respectively to the other typedata AV and TV, each of which is variable at the rate corresponding to1/2 EV.

The details of Step #307 are as follows:

Assume that the second type mode (M/2 mode) is now selected for theexposure mode, and the shutter speed TV is set at 63/4 and the aperturevalue AV at 33/4, those values being stored in the controlled shutterspeed value register TVSET and the controlled aperture value registerAVSET respectively. Next, the first type mode is selected for theexposure mode, and when the routine for identifying the exposure modeidentifies the actually selected exposure mode as the first type modethrough Steps #303, #306, #310, and #311, then, at Step #307, the datain the controlled aperture value register AVSET and that in thecontrolled shutter speed value register TVSET are shifted from values ofthe second type mode whose changing rate, that is, increment ordecrement, corresponds to 1/4 EV to values of the first type mode whosechanging rate corresponds to 1/2 EV. In the data shifting, values of thesecond type mode which do not meet the value of the first type mode areneglected. Thus the shutter speed TV of 63/4 and the aperture value AVof 33/4, both of the second type mode, are converted into 61/2 and 31/2respectively.

When the exposure mode has been converted from the second type mode tothe first type mode, the shutter speed and the aperture are shown on thedisplay in the following manner. The a of FIG. 11 is an example of howan entire representation of photographic information is shown by liquidcrystal at the display portion 11. Digits 12 to be displayed in theupper portion of the display portion 11 indicate the shutter speed (thedata in the controlled shutter speed value register TVSET) or the filmspeed (the data in the ISO register), the shutter speed graduationcorresponding to 1/2 EV when controlled by the first type mode and thefilm speed graduation corresponding to 1/3 EV. The dot 13 on the rightof the digits 12, displayed only when the digits 12 indicate the shutterspeed, signifies that the shutter spped is controlled under the secondtype mode (M/2 mode) in which increment or decrement in changing setvalues corresponds to 1/4 EV. Digits 14 to be displayed in the lowerportion of the display portion 11 indicate an aperture value (the datain the controlled aperture value register AVSET) or corrected exposurevalue (the data in the corrected exposure register ΔEV), both of thosevalues are to be altered by steps of 1/2 EV when controlled under thefirst type mode. The dot 15 on the right of the digits 14 signifiesthat, when the camera is under second type mode, aperture values orcorrected exposure values to be displayed are controlled by steps of 1/4EV.

For example, when the second type mode is selected for the exposure modeand the shutter speed TV and the aperture value AV are set at 63/4 and33/4 respectively, the photographic information display unit 11 willproduce data, including the dots 13 and 15, on the display as shown inthe b of FIG. 11. When the camera is switched to the first type mode,the shutter speed TV and the aperture value AV will be changed to 61/2and 31/2 respectively. Thus the dots 13 and 15 will disappear and thedisplay will change in appearance from the b to the c of FIG. 11. Inother words, data on display in the b and c of FIG. 11 are the same inappearance, but are different from each other in signification due tothe dots 13 and 15. If the shutter speed TV and the aperture value AVare set at 61/2 and 31/2 respectively under control of the second typemode, the display as shown in the c of FIG. 11 will result. Thus, whenthe first type mode is used, values set according to the second typemode are automatically shifted to values set according to the first typemode, and hence values of AV and TV after shifted are to be givenincrements or decrements according to the first type mode. There is nopossibility, therefore, that the values of AV and TV may be given otherincrements or decrements than those in the first type mode.

The routine for judging the exposure mode, when terminated, is followedby operation at Step #14 as shown in FIG. 3.

At Step #14, photographic information is set by the microcomputer 1under the control by alteration keys.

The details of the routine of data setting by alteration keys aredescribed next with reference to FIG. 8.

At Step #400, the microcomputer 1 turns off the film speed alterationswitch-on flag ISOONF and the exposure correction switch-on flag +/-ONF.

At Step #401, it is checked whether the film speed alteration switch SISO is on or not. If it is on, the microcomputer discriminates the filmspeed alteration to be required, and then, the program proceeds to Step#410. If the switch S ISO is not on, the program proceeds to Step #402.

A Step #410, the film speed alteration switch-on flag ISOONF is set orturned on.

At Step #411, the film speed value corresponding to 1/3 EV, which istaken as a unit for altering the film speed, is inputted to register RUD in which the degree of film speed alteration is to be stored.

At Step #412, the value stored in the register R UD is added to orsubtracted from the data in the ISO register according to whether theup-switch S TU or the down-switch S TD is changed from an off-state toan on-state. Then, the program proceeds to the next step.

At Step #402, it is checked whether the exposure compensation switchS+/- is on or not. If it is on, the exposure is regarded as requiringcorrection, and the program proceeds to Step #403. If not, the programproceeds to Step #406.

At Step #403, the exposure correction switch-on flag +/- ONF is set.

At Step #404, value corresponding to 1/2 EV is set in the register R UDin which the degree of alteration of exposure is to be stored.

At Step #405, the corrected exposure register WEV is provided with thevalue as increment or decrement, which corresponds to the value storedin the register R UD according to whether the up-switch S TU or thedown-switch S TD is turned on. Then, the program proceeds to the nextstep.

At Step #406, to which the program has proceeded from Step #402 becausethe exposure compensation switch S+/- was not on, the valuecorresponding to 1/2 EV is set in the register R UD in which the degreeof alteration is to be stored.

At Step #407, it is checked whether the exposure mode is the M/2 mode ornot. If it is, then, the program proceeds to Step #408. If not, Step#408 is skipped.

At Step #408, where the exposure mode is M/2 mode, the value set in theregister R UD at Step #406 is reduced to 1/2. Then, the program proceedsto Step #409.

At Step #409, when the exposure mode is the A mode or S mode, thecontrolled shutter speed value register TVSET is provided with thevalue, as an addend or subtrahend, stored in the register R UD in whichthe degree of alteration of exposure is to be stored, according towhether the up-switch S TU or the down-switch S TD is switched on, whilethe controlled aperture value register AVSET is provided with the valuein the register R UD as an addend or subtrahend according to whether theup-switch S AU or the down-switch S AD is turned on. When the exposuremode selected is the M mode or M/2 mode, the controlled shutter speedvalue register TVSET is provided with the value corresponding to theregister R UD in the manner of addition or subtraction according towhether the switch S TU or S TD is switched on, while the controlledaperture value register AVSET is provided with the value correspondingto the register R UD in the manner of addition or subtraction accordingto whether the switch S AU or S AD is switched on. Then, the programproceeds to the next step.

The routine for data setting by alteration keys, when terminated, isfollowed by Step #15 as shown in FIG. 3.

At Step #15, it is checked whether the AE lock flag AELF for indicatingAE lock in operation has been set or not. If it has not been set yet,measured value BV₀ is read out of the light measuring portion 2 at Step#16. If it has, no change is made in the measured value, and the programproceeds to Step #17, skipping Step #16.

At Step #17, it is discriminated whether the AE lock is in operation ornot.

The details of the routine for discrimination on AE lock are describednext with reference to FIG. 9.

At Step #500, the microcomputer 1 checks whether or not the AE lockswitch S AEL, which causes the AE lock, is on or not. If it is off, theAE lock-off flag AELOFF, which indicates that the AE lock-switch S AELis off, is set at Step #505, and then the program proceeds to the nextstep. If the AE lock switch S AEL is on, the program proceeds to Step#501.

At Step #501, it is checked whether the AE lock-off flag AELOFF has beenset or not. If it has been set already, the AE lock switch S AEL isregarded as having been off when the previous routine for discriminationon AE lock was executed (it is considered that the previous routine wasexecuted through Step #505 and subsequently the AE lock switch S AEL hasbeen turned on), and the program proceeds to Step #502. If the flagAELOFF has not been set, it is cosidered that the AE lock switch S AELwas on at the previous step for checking on AE lock, and so, the AE lockis considered to be in operation, and the program proceeds to the nextstep.

At Step #502, it is checked whether the AE lock flag AELF, whichidnicates the AE lock in operation, has been set or not. If it has beenset already, the program proceeds to Step #504. If not, the programproceeds to Step #503.

At Step #503, where the AE lock flag AELF is not set, it is consideredthat the AE lock has been started, and so, the AE lock flag AELF is set,the light-emitting diode LED2 for indicating the AE lock in operation isturned on, and AE lock-off flag AELOFF is reset or turned off, and then,the program proceeds to the next step.

At Step #504, where the AE lock flag AELF has been set already, it isconsidered that the AE lock switch S AEL was operated so as to terminatethe AE lock, so that the AE lock flag AELF is reset, the light-emittingdiode LED2 is turned off, and the AE lock-off flag AELOFF is reset. TheAE lock-off-flag AELOFF is reset as above in order to preclude the AElock from being carried out repeatedly through Steps #501, #502 and #503in case that the AE lock switch S AEL is kept in an on-state so as toterminate the AE lock.

The routine for discrimination on AE lock, when it is terminated, isfollowed by Step #18 as shown in FIG. 3.

At Step #18, the microcomputer 1 does calculations to compute theshutter speed TV and the aperture value AV for the control of theexposure.

The routine for operation for the exposure control is described indetail hereinbelow with reference to FIG. 10.

At Step #600, the microcomputer 1 computes the exposure value EV on thebasis of the luminance BV₀ of the object, fully-opened or minimum lensaperture value AV₀, and film speed SV, the first two values having beendetected and stored.

At Step #601, the above obtained exposure value EV is corrected usingthe exposure correction value WEV.

At Step #602, it is checked whether the exposure mode selected is P modeor not. If it is P mode, the program proceeds to Step #603. If not, theprogram proceeds to #604.

At Step #603, where the exposure mode selected is P mode, the shutterspeed TV and the aperture value AV are computed from the correctedexposure value EV by a known calculating method, and the values therebyobtained are stored in the controlled aperture value register AVSET andthe controlled shutter speed value register TVSET, respectively.

At Step #604, it is checked whether the exposure mode is A mode or not.If it is A mode, the set aperture value is stored in the controlledaperture value register AVSET at Step #605.

At Step #606, shutter speed TV is calculated from the corrected exposurevalue EV by using the aperture value AV preliminarily set, and theresult is stored in the controlled shutter speed value register TVSET.Then, the program proceeds to the next step.

At Step #607, it is checked whether the exposure mode selected is S modeor not. If it is S mode, the preset shutter speed value is stored in thecontrolled shutter speed value register TVSET at Step #608.

At Step #609, the aperture value AV is computed and stored in thecontrolled aperture value register AVSET. Then, the program proceeds tothe next step.

At Step #610, if the exposure mode selected is not P mode, A mode, or Smode, the preset shutter speed value TV and aperture value AV are storedin the registers TVSET and AVSET respectively.

The routine for calculation for exposure control, when terminated, isfollowed by Step #19 as shown in FIG. 3.

At Step #19, the microcomputer 1 checks whether theviewfinder-illuminating switch S LAMP is on or not. If it is on, thelight-emitting diode LED1 for illuminating the view finder is turned onat Step #20, and the illumination is maintained thereafter even if theswitch S LAMP is turned off, as long as the microcomputer 1 retains thepower source. If the switch S LAMP is not in operation, Step #20 isskipped.

At Step #21, the microcomputer 1 shows the photographic information onthe display.

The details of the routine for the display are described next withreference to FIG. 12.

At Step #700, it is checked whether the film speed alteration flagISOONF has been set or not. If it has been set already, the film speedis shown on the display at Step #707, as shown in the d of FIG. 11.

At Step #701, where the film speed alteration flag ISOONF has not beenset, it is checked whether exposure correction flag +/- ONF has been setor not. If it has been set, the program proceeds to Step #705. If not,the program proceeds to Step #702.

At Step #705, the exposure mode selected is discriminated. If it is M/2mode or M mode, the exposure correction value is displayed as shown inthe e of FIG. 11 at Step #706 (In the drawing, with the symbol +, thedisplayed value means an increment and with the symbol -, a decrement).If the exposure mode is the P, A or S mode, the operation proceeds toStep #702.

At Step #702, it is checked whether data in the exposure correctionvalue register WEV (hereinafter referred to as "exposure correctionvalue") is "0" or not. If it is "0", the shutter speed TV and theshutter value AV are shown on the display as shown in the b and c ofFIG. 11 at Step #704. If the exposure correction value is not "0", thepositive sign "+" or negative sign "-" is displayed according to whetherthe exposure correction value is positive or negative at Step #703,while the shutter speed TV and the aperture value AV are shown on thedisplay as shown the f of FIG. 11. The drawing shows that the exposurehas been corrected, so that the shutter speed value and aperture valueare increased to 1/90 sec. (TV=61/2) and 3.5 (AV=31/2), respectively.

The routine for the display, when terminated, is followed by Step #22 asshown in FIG. 3.

At Step #22, the microcomputer 1 checks whether the release switch S2 ison or not. If it is on, the microcomputer 1, at Step #23, controls theexposure according to the respective control values computed at Step #18and stored in the control shutter speed register TVSET and controlaperture value register AVSET. If the release switch S2 is off, theprogram proceeds to Step #24 skipping Step #23.

At Step #24, it is checked whether the switch S1 for preparing orsetting the camera for photographing is on or not. If it is on, theroutine for resetting and starting the timer is executed at Step #25, asat Step #9 (see FIG. 4). If it is off, the measurement using the timer,started at Step #9, is continued.

At Step #26, it is checked whether the option switch S OP2 is off ornot. If it is off, the program proceeds to Step #27, and if it is on,Step #27 is skipped.

At Step #27, it is checked whether the AE lock flag AELF has been set ornot. If it has been set (i.e., the AE lock is in operation), the programreturns to Step #10 and follows the subsequent steps as above mentioned.If the AE lock flag AELF has not been set, the program proceeds to Step#28.

At Step #28, it is checked whether the timer, started at Step #9 or Step#25, has completed the counting of the specified time (10 or 15seconds). If the specified time has not passed yet, the program revertsto Step #10 and follows the subsequent steps as described above. If thetime has passed, the program proceeds to step #4 (the routine for"stop"), and the photographing is terminated.

In the above-described embodiment, the light-emitting diode LED1 forilluminating the viewfinder is adapted to work by means of only theswitch S LAMP. In addition to this method, the switch S LAMP may beassociated with a control means for automatically turning on and off theviewfinder-illuminating light-emitting diode LED1 on the basis of themeasurement result obtained by the light measuring means for measuringthe luminance of the object. In this case, the operation of thelight-emitting diode LED1 may be controlled by such a control means ingeneral. But, when the camera is positioned rather in the dark incontrast to brightness of the object and it is difficult to see theinformation displayed in the viewfinder, the viewfinder illuminationswitch S LAMP may be operated so that the diode LED1 light up in theinside of the viewfinder. Then, the microcomputer 1 may carried out theroutine for stop in order to stop the illuminating operation of thediode LED1.

Furthermore, in addition to the above embodiment where a set value is tobe changed by steps of 1/2 EV in the first type mode and by steps of 1/4EV in the second type mode, and the dots 13 and 15 are used in thephotographic information display so as to show that displayed values areof the second type mode (See FIG. 11 (a) and (b)), a set value may bechanged at the rate of 1 EV in the first type mode, and 0.1 or 0.5 EV inthe second type mode. Then, exposure values are displayed as shown inFIG. 13, in which numeral 5 on the right side of the dots 13 and 15indicates that the set value changing rate corresponds to 0.5 EV. When0.1 EV is adopted as the changing rate, the numeral 5 is replaced withnumeral 1.

As will have bcome clear from the above description, according to thephotographic information setting device of a camera of the presentinvention, wherein the data storage by the second and third memory meansdepends on the result of the comparison by the comparing means; once aphotographer completes the correction of the film speed of a film inuse, the photographer is not required to carry out such a correctionagain in the case that he replaces the film with a new film of the sametype or when he replaces a dead battery. Consequently, the photographingoperation is effected without troublesomeness.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. A photographic information setting device for acamera comprising:an automatic film speed reading means forautomatically reading out a film speed value, of a film in use, providedon a container of the film; a first memory means for storing a filmspeed value, of an actual film, read out by the automatic film speedreading means; a second memory means for storing a film speed value, ofa film used immediately before a film in use, read out by the automaticfilm speed reading means; a third memory means for storing a film speedvalue to be used in deciding an exposure value for a camera; a filmspeed altering means for altering a film speed value stored in the thirdmemory means to another film speed value and supplying the third memorymeans with the latter value to be stored therein; a comparing means forcomparing a film speed value stored in the first memory means with onestored in the second memory means; and a controlling means forcontrolling in such a manner that, when the comparison effected by thecomparing means results in that the film speeds in the first and secondmemory means are the same, alteration of a film speed value stored inthe third memory means may not be carried out, while, when the filmspeeds in the first and second memory means are different from eachother as a result of the comparison, the film speed value in the firstmemory means may be stored in both of the second and third memory means.2. The device as claimed in claim 1, further comprising a rear lidmotion detecting means for detecting the opening and closing motion ofthe rear lid of a camera, wherein a series of operations to be effectedby the automatic film speed reading means, first memory means, comparingmeans and controlling means is carried out only once after the rear lidmotion detecting means detects that the rear lid is closed.
 3. Thedevice as claimed in claim 1, further comprising a film containerchecking means for detecting whether a container of a film bears a filmspeed value of the film, wherein, when the film container checking meansdetect that the film container bears a film speed value, alteration of afilm speed value stored in the third memory means is not carried out. 4.The device as claimed in claim 3, wherein the controlling means causesthe second memory means to store information indicating that the film inuse is in the film container which does not bear its film speed value.5. A photographic information setting device for a camera comprising:adata inputting means for inputting photographic data to be memorized; afirst memory means for storing actual data provided by the datainputting means; a second memory means for storing the previous dataprovided by the data inputting means; a third memory means for storingdata to be used for photographing, which data are of a kind similar todata stored in the first and second memories, but include data which aredifferent in numerical value from the data in the first and secondmemories; a data altering means for altering data stored in the thirdmemory means to another data and supplying the third memory means withthe latter data to be stored therein; a comparing means for comparingdata stored in the first memory means with data stored in the secondmemory means; and a controlling means for controlling in such a mannerthat, when the comparison effected by the comparing means results inthat the data in the first and second memory means are the same,alteration of data stored in the third memory means may not be carriedout.
 6. The device as claimed in claim 4, wherein when the comparison bythe comparing means results in that the data in the first and secondmemory means are different from each other, actual data provided by thedata inputting means is stored in both of the second and third memorymeans.